The present invention relates to a rotational angle detecting apparatus which converts a mechanical angular displacement into an electrical quantity in a non-contacting manner by means of a magnetic sensing element whose resistance value varies in dependence on the direction of a magnetic field.
Recently, the various control systems used in automotive vehicles include a rotational angle detector for measuring for example the position of an intake air flow measuring valve or throttle valve, and the rotational angle detector is for example of the type in which a movable contact member mechanically slides over a resistor to vary the resistance ratio or of the switch type in which a switch is turned on and off at definite angles.
These known rotational angle detectors (hereinafter referred to as angle sensors) have been manufactured in constructions in which a sensor section includes a movable rotor, bearings, etc. As a result, the manner of mounting the angle sensor to an object to be measured has become very important (if the mounting of the sensor were such that would cause shifting of the shaft, for example, the bearings would be damaged in a short period of time) and thus the manufactures have been exerting their ingenuities in finding improved manners of mounting the angle sensors.
An example of the known mounting methods designed to prevent any slight shifting of the shaft from causing damage to the bearings in the sensor section is such that since the arrangement as such is subject to hysteresis, the sensor section is specially provided with a spring so that a force is always applied in a predetermined direction to the rotor in the sensor section so as to prevent the hysteresis.